EP-A1-1 111 924 discloses the insertion of advertisements into a content signal, such as a show or film. The program that is broadcasted is scrambled. Both the program signal and the advertisement signal have their corresponding ECMs (Entitlement Control Messages) inserted, i.e. content or first ECMs and advert or second ECMs, respectively. Although the advertisement signal is scrambled with advert ECMs, the advertisement signal may be sent in the clear or scrambled using the control word of the last content ECM.
Delays may occur in a decrypting device upon transition from an advertisement to the encrypted content program signal where the control word used to scramble the content program signal is being cycled. A content ECM embedded in the content program signal must first be retrieved and loaded into a decryption device of the receiver.